PHILADELPHIA — Evan Turner has called him “the big guy.” Nick Young has dubbed him “the big fella.” For now, Andrew Bynum is nothing more than a big void.

Barring a miracle recovery between now and Wednesday night, Bynum — the 76ers’ 7-footer and their prize acquisition of the offseason — is unlikely to take the court in the team’s season opener against Denver at Wells Fargo Center.

Bynum has not practiced at all this preseason, sitting out while managing the discomfort in his right knee, and Sixers coach Doug Collins and general manager Tony DiLeo have said Bynum will not participate in basketball-related activities until he’s pain-free.

“It’s improving. It’s healing, but it’s not completely healed,” DiLeo said recently. “He’s a big investment for our team, so we just want to make sure we’re going to be cautious and we want to be sure at the beginning of the season that he’s healed and we can put him out on the court at the right time.”

On the cusp of their most-anticipated season in years, the Sixers know they will go only as far as Bynum will carry them on his surgically repaired knees.

And justifiably so. In plucking Bynum from the Los Angeles Lakers in August, the Sixers thought they were getting a guy who’d instantaneously become the Eastern Conference’s top center. Instead, they’ve gotten a guy who’s been unable to live up to that reputation, or develop chemistry and a comfort level with his new teammates, because he’s been an absentee on the floor.

The Sixers know Bynum can be that high-impact player in the East. They also view him as an investment. They traded for him aware of his history of knee ailments, and knowing his current contract is set to expire at the conclusion of this season.

Knowing what he does now, DiLeo said “absolutely yes” he still would’ve pulled the trigger on the deal.

That’s because, with Bynum, the Sixers have to be considered the favorite to knock Boston from the Atlantic Division perch it has sat upon since 2007. With Bynum, the Sixers have an interior defensive presence they’ve lacked for a decade, an offensive focal point who will command double-teams to free up looks for 3-point shooters Jason Richardson, Dorell Wright and Young, and the NBA’s second-leading rebounder last season.

Simply put, Bynum makes the Sixers better — even if he’s only available for 70, 60 or even 50 games.

“He’s a heck of a center. He’s one of the best centers in the league — in the top two of them,” Cleveland coach Byron Scott said on a trip to Wells Fargo Center this preseason. “When you look at it, I’ve always thought of him being right there with (the Lakers’) Dwight Howard. Probably not the defensive player Dwight Howard is, but probably a better offensive player.

“If (Bynum) is healthy and he wants to play, he can be a monster. That gives them a different element that they haven’t had the last couple years — a guy you can throw the ball to in the post who, when the game’s on the line, can deliver.”

At this stage, all of that seems like a pipe dream for the Sixers. Bynum’s knees cannot endure running or any sort of impact activity, which means he’s either had to watch practice from the bench or from the elliptical machines located just off the floor at PCOM. And when Bynum is finally declared a go, there’s no telling how quickly he’ll be able to play at game speed, either.

Collins said he doesn’t like to think about that, saying that’s “all hypothetical.”

Here’s something that isn’t so hypothetical: Bynum, who gutted out injuries in the 2010 playoffs en route to helping the Lakers win the NBA crown that season, has said he’s willing to play through pain — and he’s shown he can do so at an elite level. Only four players had more double-doubles last season than Bynum, who averaged 18.7 points and 11.8 rebounds.

“I’m more psychologically feeling like it stinks not being able to play,” Bynum said. “It’s tough coming and staying motivated and things like that. My teammates are there. They’re all patting me on the back, wanting me to get back. That helps. My coaches, they’ve been a great pleasure for me to talk to also and advocate being healthy and getting back. That’s the big picture.”

With or without Bynum, the Sixers will not change their style: a high-tempo game buoyed by transition 3-pointers. Collins has a young team, with swift power forward Thad Young, second-year center Lavoy Allen, third-year small forward Turner and fourth-year point guard Jrue Holiday expected to be in the starting lineup.

As much as he’s had to install plays and coach Xs and Os this preseason, Collins has had to teach his guys how to play confidently until Bynum is healthy enough to join them.

“As a coach, the most important thing you do is the message you send to your team is, ‘We’re good and we can win. We’re good and we can win,’” Collins said recently. “We’re not going to look over at a lifeline and say, ‘Let’s wait for our lifeline to get back.’ You can’t do that.

“From a coaching standpoint, I have to let my players know we’re good enough to win. That’s who we can be. And when Andrew comes back, maybe we can be even better and take it to another level.”